This invention constitutes an improvement in circuit card guides of the type exemplified by my prior U.S. Pat. No. 3,258,650, issued June 28, 1966. That patent discloses a circuit card guide comprising a channel shaped element wherein the side walls extend inwardly to terminate in edges spaced from one another sufficiently to permit entry of a circuit card therebetween while exerting resilient clamping pressure against the card throughout the length of the guide.
Other circuit card guides have been constructed so as to exert the resilient clamping force only at spaced points along the guide. For instance, Calabro U.S. Pat. No. 3,231,785, issued Jan. 25, 1966 discloses a circuit card guide comprising an elongated channel shaped element including spaced pairs of opposed fingers extending from the side walls in cantelever fashion, the free end portions providing the gripping contact with the circuit card.
Opposed pairs of cantilevered gripping fingers are also seen in a circuit card guide manufactured by Scanbe Manufacturing Corporation of Monterey Park, Cal. and identified as Guide No. 10067.
In each of the foregoing, the cantilever structure is subject to breakage or distortion under conditions of abuse in handling or in circuit card insertion. Moreover, the gripping fingers are formed by an interruption in the side wall with a consequent sacrifice of structural integrity.
The shortcoming inherent in cantilevered gripping elements has been avoided by structures wherein the gripping element is supported at both ends in order to form a leaf spring, the element being displaced inwardly toward the circuit card to resiliently press thereagainst. One such structure is seen in International Business Machines, Inc., Technical Disclosure Bulletin, Vol. 17, No. 1, June, 1974, page 128. This structure comprises an elongate channel member having the edges of the base portion and the basal region of the side walls cut away at the juncture thereof, all three walls being displaced inwardly of the channel to provide three resilient gripping members. The walls are resilient throughout virtually their entire length, being absent any reinforcing provision in the side walls.
Another similar guide is the subject of British patent No. 1,109,701 published Apr. 10, 1968 to McMurdo Instrument Company Limited. This patent describes a circuit card guide including a channel having one or more webs, each formed integrally of the guide and being attached to a wall of the channel only at its ends and being free of attachment intermediate its ends, the intermediate free portion extending into the channel and being resilient so as to grip a card inserted in the channel. The resilient gripping elements are formed by a slot extending downwardly from the upper surface of the sidewall of substantial thickness.